I've had an issue recently with my 2007 328i (stock) where when approaching a stop the Engine will suddenly drop in RPM and then go back up to idle speed when I clutch in. Example:

Slowing to stoplight in fourth. When RPM reaches 1500, I clutch in, RPM drops to 500, then increase immediately to 800-1000 (standard idle).

I wouldn't worry much except the other day it actually killed the engine. I have no warning lights on. At first I thought maybe the clutch was dragging a bit but the more I notice the issue, the less I think that's the problem. It seems to be more prevalent when the engine is warm. Any ideas?

I've had an issue recently with my 2007 328i (stock) where when approaching a stop the Engine will suddenly drop in RPM and then go back up to idle speed when I clutch in. Example:

Slowing to stoplight in fourth. When RPM reaches 1500, I clutch in, RPM drops to 500, then increase immediately to 800-1000 (standard idle).

I wouldn't worry much except the other day it actually killed the engine. I have no warning lights on. At first I thought maybe the clutch was dragging a bit but the more I notice the issue, the less I think that's the problem. It seems to be more prevalent when the engine is warm. Any ideas?

Standard idle is ~600 without AC and ~700 with AC. If your fully warmed up idle is ~1000, that's a problem/symptom in itself.

Standard idle is ~600 without AC and ~700 with AC. If your fully warmed up idle is ~1000, that's a problem/symptom in itself.

I was just guessing at the time, I've been paying more attention to the problem and it seems like ~700 is normal (it's summer in Iowa, AC is on all the time). When it drops down it's definitely going below 500 rpm.

I've had the exact same thing for a few weeks now in my 328. It seems to happen usually when coasting then then putting the clutch in around 1500 rpm, and if I keep the clutch engaged down to 1000 rpm as I coast it doesn't drop below 650 when I finally put the clutch in. I don't want to have to think about this every time I come to a stop though. No codes on the dash, and I've been thinking about getting a BT tool and doing some diagnostics but I haven't had the time yet.

I recently discovered that the previous owner did the intake "silencer" delete and there was a leak in the epoxy, so for now I siliconed the hole and I have a stock tube coming in in a few days. I thought that was going to fix it because it's after the MAF, and although it hasn't stalled since then it has dropped to about 400-500 rpm a few times. I'll see in a few days if the stock intake tube helps, but I doubt it.

Also just did spark plugs, filters, oil (I'm at 80k) and techron a few tanks ago. No noticeable change. I found a few other threads here with similar problems, but not any real solutions to this exact problem.